The goals of the Immunology Committee of the Childrens Cancer Study Group are to study the clinical immunobiology of childhood malignancy, to test promising approaches to the immunologic treatment of cancer, and to provide a resource for immunologic expertise in the Childrens Cancer Study Group. The specific aims of the present proposal are to continue to use monoclonal anbitodies to identify phenotypically distinct subsets of acute lymphocytic and nonlymphocytic leukemic cells, to determine whether these subsets show clinically distinct outcomes in CCSG studies; and to continue diagnostic and prognostic studies of neuroblastoma. For this purpose, tumor associated markers including serum neuron specific enolase, serum ferritin, monoclonal antibody and anti-NSE serum reactivity, and urinary metabolites will be evaluated. The Committee will also continue as a resource of immunologic expertise for the Childrens Cancer Study Group. This will be accomplished through meetings and workshops of the Immunology Committee, and the contribution of their expertise to the writing of therapeutic protocols. We will also continue to conduct non-therapeutic immunology protocols, including studies on the prognostic significance of leukocyte 5a antigen expression by patients with ALL (I-01) and Fc and C' receptor expression by ANLL cells (I-01). Also continued will be immunobiologic studies of patients with histiocytosis.